"""
Problem:
The prime factors of 13195 are 5,7,13 and 29. What is the largest prime factor of a given number N?
e.g. for 10, largest prime factor = 5. For 17, largest prime factor = 17.
"""

from __future__ import print_function

n = int(input())
prime = 1
i = 2
while i * i <= n:
    while n % i == 0:
        prime = i
        n //= i
    i += 1
if n > 1:
    prime = n
print(prime)
